我們利用原子力顯微鏡(AFM)之探針以“機械式”的方法對在雲母片(mica)上厚度約12奈米高的脂質膜層做表面奈米蝕刻、以及以“電場式”方法對矽晶片(silicon wafer)與金表面上多種厚度之脂質膜層製造出表面奈米蝕刻。脂質膜是生物薄膜的主要成分，為軟物質的一種。在一個親水的基板上會因“自組性質”而自動排列成一個很均勻平整的薄膜，若使用原子力顯微鏡的接觸模式(contact mode)使探針接觸到或行走於脂質膜上，其探針作用於脂質膜上之作用力大小足以影響脂質膜之表面型態，例如針尖吸附脂質分子或刮開表面。因此我們可以控制探針之針尖軌跡與作用力大小來製作出奈米圖案。而另一種“電場式”的方法為在矽晶片上加上一個正偏壓，使得針尖與矽晶片間由於E=V/d之作用而產生強大的電場以及電流將通過脂質層，強大的電流可以加熱脂質分子使得具有高動能的分子離開矽晶片表面形成空洞而製造出圖形。 然而，在雲母片上形成的直線圖形不論是凹線或凸線並非呈靜止狀態而是會隨著時間發生長度變短而寬度變長、且面積約略相等的現象(觀測時間約數十分鐘至數小時)。我們於是利用此性質來模擬脂質膜之張力常數以及膜與雲母片間阻力係數比值(β/γ)相對於溫度的關係，並且得到β/γ值隨著溫度升高而變小。其表示圖形變化速率隨溫度增高而加快，我們因而推測其溫度升高使得脂質分子含有較大流動率，故β/γ增大。而我們也發現室溫下矽晶片上蝕刻產生的凹線圖案是不會隨時間而改變的。此現象表示脂質膜與雲母片間之阻力很小但與矽晶片間的阻力在室溫下卻大到足以阻止脂質膜移動。 Nanoscale-lithography was performed using AFM tips on lipid membranes of 12 nm thickness over mica through “mechanical method” and also on membranes of various thickness over silicon wafer through “electrostatic method”. Phospholipid is one of the main components of biological membranes, and also a kind of soft matter. Lipid molecules can assemble into extremely uniform thin films due to its “self-assembly” property. If we use the AFM tip in contact mode to touch or move over lipid membranes, the interaction between tip and membrane is strong enough to change the surface morphology. For example, the tip may absorb lipid molecules or scrape the membrane films. Therefore we can make nano-patterns by controlling the tip-membrane interaction and the tip’s trajectory. Besides, “electrostatic method” is an approach giving a bias voltage between the silicon wafer and the tip to enable a strong electric field as well as current passing through lipid membranes. The current causes Joule heating and that enables lipid molecules to be removed from the silicon wafer to form patterns. However, the indentation straight line formed on membranes over mica is not static but evolves with time, such as length contaction as well as width expansion. However, the hole area remains approximately the same (The observation time is up to three hours). Hence we use the observation to derive the ratio of resistance between membrane and mica to membrane surface tension (β/γ). We find that the value of β/γ that depends on temperature decreases with temperature, which suggests that the resistance decreases with temperature. This is clue to the mobility increased as temperature was raised. Furthermore, we observed that the indentation lines on membrane of 12 nm thickness over the silicon wafer at room temperature are not deformed with time. This indicates that the resistance (β) is large enough to prevent from membrane movement at R.T.
